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Abstract:

A reflecting resin sheet provides a reflecting resin layer at the side of
a light emitting diode element and includes a first release substrate and
the reflecting resin layer provided on one surface in a thickness
direction of the first release substrate. In the first release substrate
and the reflecting resin layer, a through hole extending therethrough in
the thickness direction is formed corresponding to the light emitting
diode element so as to allow an inner circumference surface of the
through hole in the reflecting resin layer to be disposed in opposed
relation to a side surface of the light emitting diode element.

Claims:

1. A reflecting resin sheet, for providing a reflecting resin layer at
the side of a light emitting diode element, comprising: a first release
substrate and the reflecting resin layer provided on one surface in a
thickness direction of the first release substrate, wherein, in the first
release substrate and the reflecting resin layer, a through hole
extending therethrough in the thickness direction is formed corresponding
to the light emitting diode element so as to allow an inner circumference
surface of the through hole in the reflecting resin layer to be disposed
in opposed relation to a side surface of the light emitting diode
element.

2. A method for producing a light emitting diode device comprising the
steps of: providing a reflecting resin layer on one surface in a
thickness direction of a first release substrate, forming a through hole
in the first release substrate and the reflecting resin layer such that
the through hole extends therethrough in the thickness direction to
prepare a reflecting resin sheet in which the through hole is formed
corresponding to the light emitting diode element so as to allow an inner
circumference surface of the through hole in the reflecting resin layer
to be disposed in opposed relation to a side surface of the light
emitting diode element, laminating the reflecting resin sheet on one
surface in the thickness direction of a substrate so as to bring the
reflecting resin layer into contact with the substrate, disposing a light
emitting diode element on one surface in the thickness direction of the
substrate, bringing the reflecting resin layer into close contact with a
side surface of the light emitting diode element, and peeling off the
first release substrate from the reflecting resin layer.

3. The method for producing the light emitting diode device according to
claim 2, wherein in the step of bringing the reflecting resin layer into
close contact with the side surface of the light emitting diode element,
the first release substrate is pressed toward the substrate.

4. The method for producing the light emitting diode device according to
claim 2, wherein the substrate is a diode board and in the step of
disposing the light emitting diode element on one surface in the
thickness direction of the substrate, the light emitting diode element is
disposed in the through hole of the reflecting resin sheet and is flip
mounted on the substrate.

5. The method for producing the light emitting diode device according to
claim 2, wherein the substrate is a second release substrate, and the
method for producing the light emitting diode device further comprising
the steps of: peeling off the substrate from the reflecting resin layer
and the light emitting diode element and flip mounting the light emitting
diode element on the diode board.

6. A light emitting diode device comprising: a diode board, a light
emitting diode element flip mounted on the diode board, and a reflecting
resin layer in close contact with a side surface of the light emitting
diode element.

7. The light emitting diode device according to claim 6 further
comprising: a phosphor layer formed on one surface in the thickness
direction of the light emitting diode element.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority from Japanese Patent
Application No. 2011-089939 filed on Apr. 14, 2011, the contents of which
are hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a reflecting resin sheet, a light
emitting diode device, and a producing method thereof, to be specific, to
a producing method of a light emitting diode device, a reflecting resin
sheet used in the producing method, and a light emitting diode device
obtained by the producing method of the light emitting diode device.

[0004] 2. Description of Related Art

[0005] In recent years, as a light emitting device that is capable of
emitting high-energy light, a white light emitting device has been known.
In the white light emitting device, for example, a diode board; an LED
(light emitting diode) laminated thereon, emitting blue light; a phosphor
layer that can convert the blue light into yellow light and covers the
LED; and an encapsulating layer that encapsulates the LED are provided.
The white light emitting device emits high-energy white light by color
mixing of the blue light emitted from the LED, which is encapsulated by
the encapsulating layer and to which electric power is supplied from the
diode board, transmitting through the encapsulating layer and the
phosphor layer, and the yellow light that is converted in wavelength from
a part of the blue light in the phosphor layer.

[0006] As a method for producing the white light emitting device, for
example, the following method has been proposed (ref: for example,
Japanese Unexamined Patent Publication No. 2005-191420).

[0007] The proposed method is as follows. That is, a base, which has a
board portion and a white reflecting frame portion protruding from the
circumference portion thereof toward the upper side, is first formed.
Next, a semiconductor light emitting element is subjected to a wire
bonding in a bottom portion of a concave portion, which is formed at the
center of the board portion by the reflecting frame portion, so as to be
spaced apart from the inner side of the reflecting frame portion.

[0008] Next, a mixture of a phosphor and an epoxy resin in a liquid state
is filled in the concave portion by application, subsequently the
phosphor is spontaneously precipitated in the bottom portion of the
concave portion, and then the epoxy resin is heat cured.

[0009] In the white light emitting device obtained by the method proposed
in Japanese Unexamined Patent Publication No. 2005-191420, the phosphor
layer (a wavelength conversion layer) that contains the phosphor formed
by a precipitation at high concentrations is defined in a region at the
upper side of the semiconductor light emitting element and an
encapsulating portion that contains the epoxy resin at high
concentrations is defined in a region at the upper side of the phosphor
layer.

[0010] In the white light emitting device, the semiconductor light
emitting element radially emits the blue light. Of the emitted blue
light, a part thereof emitted from the semiconductor light emitting
element toward the upper side is converted into the yellow light in the
phosphor layer and the remaining light transmits through the phosphor
layer. The blue light emitted from the semiconductor light emitting
element toward the side is reflected at the reflecting frame portion and
then toward the upper side. The white light emitting device in Japanese
Unexamined Patent Publication No. 2005-191420 emits the white light by
color mixing of the blue light and the yellow light.

SUMMARY OF THE INVENTION

[0011] However, in the white light emitting device obtained by the
producing method in Japanese Unexamined Patent Publication No.
2005-191420, there is a disadvantage that the semiconductor light
emitting element is spaced apart from the reflecting frame portion, so
that a part of the light emitted from the semiconductor light emitting
element toward the side is absorbed in the encapsulating portion before
being reflected at the reflecting frame portion and as a result,
extraction efficiency of the light is reduced.

[0012] It is an object of the present invention to provide a light
emitting diode device that is capable of improving extraction efficiency
of light, a producing method thereof, and a reflecting resin sheet used
in the producing method.

[0013] A reflecting resin sheet of the present invention, for providing a
reflecting resin layer at the side of a light emitting diode element,
includes a first release substrate and the reflecting resin layer
provided on one surface in a thickness direction of the first release
substrate, wherein, in the first release substrate and the reflecting
resin layer, a through hole extending therethrough in the thickness
direction is formed corresponding to the light emitting diode element so
as to allow an inner circumference surface of the through hole in the
reflecting resin layer to be disposed in opposed relation to a side
surface of the light emitting diode element.

[0014] In the reflecting resin sheet, the through hole is formed
corresponding to the light emitting diode element so as to allow the
inner circumference surface of the through hole in the reflecting resin
layer to be disposed in opposed relation to the side surface of the light
emitting diode element. Accordingly, the light emitting diode element can
be disposed in the through hole such that the inner circumference surface
of the through hole in the reflecting resin layer is disposed in opposed
relation to the side surface of the light emitting diode element.
Therefore, it is possible to reliably bring the reflecting resin layer
into close contact with the side surface of the light emitting diode
element.

[0015] Therefore, in the obtained light emitting diode device, light
emitted from the light emitting diode element is reflected by the
reflecting resin layer before being absorbed by another member.

[0016] As a result, the extraction efficiency of the light can be
improved.

[0017] A method for producing a light emitting diode device of the present
invention includes the steps of providing a reflecting resin layer on one
surface in a thickness direction of a first release substrate, forming a
through hole in the first release substrate and the reflecting resin
layer such that the through hole extends therethrough in the thickness
direction to prepare the above-described reflecting resin sheet,
laminating the reflecting resin sheet on one surface in the thickness
direction of a substrate so as to bring the reflecting resin layer into
contact with the substrate, disposing a light emitting diode element on
one surface in the thickness direction of the substrate, bringing the
reflecting resin layer into close contact with a side surface of the
light emitting diode element, and peeling off the first release substrate
from the reflecting resin layer.

[0018] In this method, the reflecting resin layer is brought into close
contact with the side surface of the light emitting diode element.

[0019] Therefore, in the light emitting diode device obtained by the
above-described method, the light emitted from the light emitting diode
element is reflected by the reflecting resin layer before being absorbed
by another member.

[0020] As a result, the extraction efficiency of the light can be
improved.

[0021] In the method for producing the light emitting diode device of the
present invention, it is preferable that in the step of bringing the
reflecting resin layer into close contact with the side surface of the
light emitting diode element, the first release substrate is pressed
toward the substrate.

[0022] In this method, the first release substrate is pressed toward the
substrate. Accordingly, the reflecting resin layer sandwiched between the
first release substrate and the substrate in the thickness direction
fluidly moves to the side. Therefore, when the inner circumference
surface of the through hole in the reflecting resin layer is disposed in
opposed relation to the side surface of the light emitting diode element,
the reflecting resin layer can be reliably brought into close contact
with the side surface of the light emitting diode element.

[0023] In the method for producing the light emitting diode device of the
present invention, it is preferable that the substrate is a diode board
and in the step of disposing the light emitting diode element on one
surface in the thickness direction of the substrate, the light emitting
diode element is disposed in the through hole of the reflecting resin
sheet and is flip mounted on the substrate.

[0024] According to this method, when the reflecting resin sheet formed
with the through hole is accurately disposed with respect to the
substrate, which is the diode board, by subsequently disposing the light
emitting diode element in the through hole of the reflecting resin sheet,
it is possible to allow easy, accurate, and reliable positioning of the
light emitting diode element with respect to the substrate, while the
light emitting diode element is allowed to be flip mounted on the
substrate.

[0025] In the method for producing the light emitting diode device of the
present invention, it is preferable that the substrate is a second
release substrate, and the method for producing the light emitting diode
device further includes the steps of peeling off the substrate from the
reflecting resin layer and the light emitting diode element and flip
mounting the light emitting diode element on the diode board.

[0026] In this method, the light emitting diode element which has the side
surface thereof in close contact with the reflecting resin layer and from
which the substrate, which is the second release substrate, is peeled off
is flip mounted on the diode board, so that the light emitting diode
device can be easily produced.

[0027] A light emitting diode device of the present invention includes a
diode board, a light emitting diode element flip mounted on the diode
board, and a reflecting resin layer in close contact with a side surface
of the light emitting diode element.

[0028] In the light emitting diode device, light emitted from the light
emitting diode element is reflected by the reflecting resin layer before
being absorbed by another member.

[0029] As a result, the extraction efficiency of the light can be
improved.

[0030] It is preferable that the light emitting diode device of the
present invention further includes a phosphor layer formed on one surface
in the thickness direction of the light emitting diode element.

[0031] The light emitting diode device can emit high-energy white light by
color mixing of the light emitted from the light emitting diode element
and light that is converted in wavelength by the phosphor layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 shows a plan view of one embodiment of a light emitting
diode device of the present invention.

[0033]FIG. 2 shows process drawings for illustrating one embodiment of a
method for producing the light emitting diode device of the present
invention:

[0034] (a) illustrating a step of providing a reflecting resin layer on
the upper surface of a first release substrate,

[0035] (b) illustrating a step of forming through holes in the first
release substrate and the reflecting resin layer,

[0036] (c) illustrating a step of laminating a reflecting resin sheet on
the upper surface of a diode board, and

[0037] (d) illustrating a step of disposing light emitting diode elements
in the through holes of the reflecting resin sheet.

[0038] FIG. 3 shows process drawings for illustrating one embodiment of a
method for producing the light emitting diode device of the present
invention, subsequent to FIG. 2:

[0039] (e) illustrating a step of pressing the first release substrate
toward the diode board,

[0040] (f) illustrating a step of detaching a buffer sheet and peeling off
the first release substrate, and

[0042]FIG. 4 shows process drawings for illustrating another embodiment
(an embodiment in which a second release substrate is used) of a method
for producing the light emitting diode device of the present invention:

[0043] (a) illustrating a step of providing the reflecting resin layer on
the upper surface of the first release substrate,

[0044] (b) illustrating a step of forming the through holes in the first
release substrate and the reflecting resin layer,

[0045] (c) illustrating a step of laminating the reflecting resin sheet on
the upper surface of the second release substrate, and

[0046] (d) illustrating a step of disposing the light emitting diode
elements in the through holes of the reflecting resin sheet.

[0047]FIG. 5 shows process drawings for illustrating another embodiment
(an embodiment in which the second release substrate is used) of a method
for producing the light emitting diode device of the present invention,
subsequent to FIG. 4:

[0048] (e) illustrating a step of pressing the first release substrate
toward the diode board,

[0049] (f) illustrating a step of detaching the buffer sheet,

[0050] (g) illustrating a step of individualizing the light emitting diode
elements, and

[0052]FIG. 1 shows a plan view of one embodiment of a light emitting
diode device of the present invention. FIGS. 2 and 3 show process
drawings for illustrating one embodiment of a method for producing the
light emitting diode device of the present invention.

[0053] In FIGS. 1 and 3(f), a light emitting diode device 1 includes a
diode board 2 as a substrate, a light emitting diode element 3 flip
mounted on the diode board 2, a phosphor layer 5 laminated on the upper
surface (one surface in a thickness direction) of the light emitting
diode element 3, and a reflecting resin layer 4 provided at the lateral
side of the light emitting diode element 3 and the phosphor layer 5.

[0054] A plurality of the light emitting diode devices 1 are provided to
be spaced apart from each other in a plane direction (to be specific, a
right-left direction of the paper surface and a front-rear direction of
the paper surface shown by the arrows in FIG. 1). To be specific, a
plurality of the light emitting diode devices 1 include the common diode
board 2 and on one piece of the diode board 2, a plurality of the light
emitting diode elements 3, the reflecting resin layer 4 provided at the
side thereof, and a plurality of the phosphor layers 5 provided on the
respective light emitting diode elements 3 are provided. A plurality of
the light emitting diode devices 1 form an assembly sheet 24.

[0055] As shown in the dash-dot lines in FIG. 1 and the dash-dot lines in
FIG. 3(f), the diode board 2 and the reflecting resin layer 4, which are
located between the light emitting diode elements 3, are subjected to a
cutting (dicing, described later) process along the thickness direction,
so that, as shown in FIG. 3(g), it is also possible to obtain the
individualized light emitting diode devices 1.

[0056] The diode board 2 is formed into a generally rectangular flat plate
shape. To be specific, the diode board 2 is formed of a laminated board
in which a conductive layer, as a circuit pattern, is laminated on an
insulating board. The insulating board is formed of, for example, a
silicon board, a ceramic board, a polyimide resin board, or the like.
Preferably, the insulating board is formed of the ceramic board, to be
specific, a sapphire (Al2O3) board. The conductive layer is
formed of, for example, a conductor such as gold, copper, silver, or
nickel. The conductors can be used alone or in combination.

[0057] The conductive layer includes a terminal 6.

[0058] The terminals 6 are formed at spaced intervals in the plane
direction on the upper surface of the insulating board and are formed
into a pattern corresponding to electrode portions 8 to be described
later. Although not shown, the terminal 6 is electrically connected to an
electric power supply portion via the conductive layer.

[0059] The diode board 2 has a thickness in the range of, for example, 25
to 2000 μm, or preferably 50 to 1000 μm.

[0060] The light emitting diode element 3 is provided on the upper surface
(one surface in the thickness direction) of the diode board 2 and is
formed into a generally rectangular shape in plane view. A plurality of
the light emitting diode elements 3 are, on the upper surface of one
piece of the diode board 2, arranged to be aligned at spaced intervals to
each other in the plane direction (in the right-left direction and the
front-rear direction shown by the arrows in FIG. 1).

[0061] As shown in FIG. 3(f), each of the light emitting diode elements 3
includes a light semiconductor layer 7 and the electrode portions 8
formed on the lower surfaces thereof.

[0062] The light semiconductor layer 7 is formed into a generally
rectangular shape in plane view corresponding to the outer shape of the
light emitting diode element 3 and is formed into a generally rectangular
shape in sectional view that is long in the plane direction.

[0063] Although not shown, for example, the light semiconductor layer 7
includes a buffer layer, an N-type semiconductor layer, a light emitting
layer, and a P-type semiconductor layer that are successively laminated
in a descending order. The light semiconductor layer 7 is formed of a
known semiconductor material and is formed by a known growth method such
as an epitaxial growth method. The light semiconductor layer 7 has a
thickness in the range of, for example, 0.1 to 500 μm, or preferably
0.2 to 200 μm.

[0064] The electrode portion 8 is electrically connected to the light
semiconductor layer 7 and is formed so as to be included in the light
semiconductor layer 7 when projected in the thickness direction. The
electrode portion 8 includes, for example, an anode electrode that is
connected to the P-type semiconductor layer and a cathode electrode that
is formed in the N-type semiconductor layer.

[0065] The electrode portion 8 is formed of a known conductive material
and has a thickness in the range of, for example, 10 to 1000 nm.

[0066] The phosphor layer 5 is formed into a generally rectangular shape
in plane view corresponding to the outer shape of the light emitting
diode element 3 and is formed over the entire upper surface of the light
emitting diode element 3.

[0067] The phosphor layer 5 is formed of, for example, a phosphor
composition that contains a phosphor.

[0068] The phosphor composition contains, for example, the phosphor and a
resin.

[0069] An example of the phosphor includes a yellow phosphor that is
capable of converting blue light into yellow light. An example of the
phosphor includes a phosphor obtained by doping a metal atom such as
cerium (Ce) or europium (Eu) into a composite metal oxide, a metal
sulfide, or the like.

[0070] To be specific, examples of the phosphor include garnet type
phosphor having a garnet type crystal structure such as
Y3Al5O12:Ce (YAG (yttrium aluminum garnet):Ce),
(Y,Gd)3Al5O12:Ce, Tb3Al3O12:Ce,
Ca3Sc2Si3O12:Ce, and
Lu2CaMg2(Si,Ge)3O12:Ce; silicate phosphor such as
(Sr,Ba)2SiO4:Eu, Ca3SiO4Cl2:Eu,
Sr3SiO5:Eu, Li2SrSiO4:Eu, and
Ca3Si2O7:Eu; aluminate phosphor such as
CaAl12O19:Mn and SrAl2O4:Eu; sulfide phosphor such as
ZnS:Cu, Al, CaS:Eu, CaGa2S4:Eu, and SrGa2S4:Eu;
oxynitride phosphor such as CaSi2O2N2:Eu,
SrSi2O2N2:Eu, BaSi2O2N2:Eu, and
Ca-α-SiAlON; nitride phosphor such as CaAlSiN3:Eu and
CaSi5N8:Eu; and fluoride-based phosphor such as
K2SiF6:Mn and K2TiF6:Mn. Preferably, garnet type
phosphor is used, or more preferably, Y3Al5O12:Ce (YAG) is
used.

[0071] The phosphors can be used alone or in combination of two or more.

[0072] The mixing ratio of the phosphor with respect to the phosphor
composition is, for example, 1 to 50 mass %, or preferably 5 to 30 mass
%. The mixing ratio of the phosphor is, for example, 1 to 100 parts by
mass, or preferably 5 to 40 parts by mass per 100 parts by mass of a
resin.

[0073] The resin is a matrix in which the phosphor is dispersed,
including, for example, transparent resins such as silicone resin, epoxy
resin, and acrylic resin. Preferably, the silicone resin is used from the
viewpoint of durability.

[0074] The silicone resin has, in its molecule, a main chain mainly
composed of the siloxane bond (--Si--O--Si--) and a side chain, which is
bonded to silicon atoms (Si) of the main chain, composed of an organic
group such as an alkyl group (for example, a methyl group and the like)
or an alkoxyl group (for example, a methoxy group).

[0076] The silicone resin has a kinetic viscosity at 25° C. in the
range of, for example, 10 to 30 mm2/s.

[0077] The resins can be used alone or in combination of two or more.

[0078] The mixing ratio of the resin is, for example, 50 to 99 mass %, or
preferably 70 to 95 mass % with respect to the phosphor composition.

[0079] The phosphor and the resin are blended at the above-described
mixing ratio and are stirred and mixed, so that the phosphor composition
is prepared.

[0080] The phosphor layer 5 can also be formed of, for example, a ceramic
of a phosphor (phosphor ceramic plate). In that case, the above-described
phosphor is used as a ceramic material and by sintering such a ceramic
material, the phosphor layer 5 (phosphor ceramic) is obtained.

[0081] The phosphor layer 5 has a thickness in the range of, for example,
100 to 1000 μM, preferably 200 to 700 μm, or more preferably 300 to
500 μm.

[0082] The reflecting resin layer 4 is formed on the upper surface of the
diode board 2 such that, when the reflecting resin layer 4 is projected
in the thickness direction, the circumference end edge thereof is at the
same position as that of the circumference end edge of the diode board 2.
Also, when projected in the thickness direction, the reflecting resin
layer 4 is formed in a region at least other than the regions where the
light emitting diode elements 3 (to be specific, the electrode portions
8) are formed.

[0083] That is, the reflecting resin layer 4 is disposed so as to surround
the respective side surfaces of the light emitting diode elements 3 and
the phosphor layers 5 and also cover the lower surfaces of the light
semiconductor layers 7 exposed from the electrode portions 8.

[0084] To be specific, as shown in FIG. 1, the reflecting resin layer 4 is
formed into a generally rectangular frame shape on both outer sides of
each of the light emitting diode elements 3 and each of the phosphor
layers 5 in the right-left direction and in the front-rear direction.
With its frame portion being arranged to be continuously aligned in the
right-left direction and in the front-rear direction, the reflecting
resin layer 4 is formed into a generally grid shape in plane view over
the upper surface of one piece of the diode board 2.

[0085] To be more specific, as shown in FIG. 3(f), the reflecting resin
layer 4 is in close contact with each of the respective outer side
surfaces of the light emitting diode elements 3 and the phosphor layers
5, to be specific, each of the surfaces of the left surface, the right
surface, the front surface (ref: FIG. 1), and the rear surface (ref: FIG.
1) of each of the light emitting diode elements 3 and each of the
phosphor layers 5. The reflecting resin layer 4 also exposes the upper
surfaces of the phosphor layers 5.

[0086] At the lower side of the light semiconductor layer 7, lower space
12 (ref: FIG. 2(d)) each corresponding to the thickness of each of the
electrode portions 8 are formed and are also filled with the reflecting
resin layer 4. In this way, the reflecting resin layer 4 is also in close
contact with the lower surfaces of the light semiconductor layers 7
exposed from the electrode portions 8 and the side surfaces of the
electrode portions 8.

[0087] The upper surface of the reflecting resin layer 4 is formed to be
substantially flush with the upper surfaces of the phosphor layers 5 in
the plane direction.

[0088] The above-described reflecting resin layer 4 contains, for example,
a light reflecting component. To be specific, the reflecting resin layer
4 is formed of a reflecting resin composition that contains a resin and
the light reflecting component.

[0090] The light reflecting component is, for example, a white compound.
To be specific, an example of the white compound includes a white
pigment.

[0091] An example of the white pigment includes a white inorganic pigment.
Examples of the white inorganic pigment include an oxide such as titanium
oxide, zinc oxide, and zirconium oxide; a carbonate such as white lead
(lead carbonate) and calcium carbonate; and a clay mineral such as
kaoline (kaolinite).

[0092] As the white inorganic pigment, preferably, the oxide is used or
more preferably, the titanium oxide is used.

[0093] The titanium oxide can have characteristics such as a high degree
of whiteness, a high light reflectivity, excellent hiding characteristics
(hiding power), excellent coloring characteristics (coloring power), a
high dispersibility, an excellent weather resistance, and a high chemical
stability.

[0095] A crystal structure of the titanium oxide is not particularly
limited. For example, the crystal structure thereof is rutile, brookite
(pyromelane), anatase (octahedrite), or the like. Preferably, the crystal
structure thereof is rutile.

[0096] A crystal system of the titanium oxide is not particularly limited.
For example, the crystal system thereof is a tetragonal system, an
orthorhombic system, or the like. Preferably, the crystal system thereof
is the tetragonal system.

[0097] When the crystal structure and the crystal system of the titanium
oxide are rutile and the tetragonal system, respectively, it is possible
to effectively prevent a reduction of the reflectance with respect to
light (to be specific, visible light, among all, the light around the
wavelength of 450 nm) even in a case where the reflecting resin layer 4
is exposed to a high temperature for a long time.

[0098] The light reflecting component is in the form of a particle. The
shape thereof is not limited and examples of the shape thereof include,
for example, a sphere shape, a plate shape, and a needle shape. An
average value of the maximum length (in a case of the sphere shape, the
average particle size) of the light reflecting component is in the range
of, for example, 1 to 1000 nm. The average value of the maximum length is
measured by using a laser diffraction scattering particle size analyzer.

[0099] The mixing ratio of the light reflecting component per 100 parts by
mass of the resin is, for example, 0.5 to 90 parts by mass, or preferably
1.5 to 70 parts by mass from the viewpoint of the coloring
characteristics, the light reflectivity, and handling ability of the
reflecting resin composition.

[0100] The above-described light reflecting component is uniformly
dispersed and mixed into the resin.

[0101] In addition, a filler can further be added into the reflecting
resin composition. That is, the filler can be used in combination with
the light reflecting component (to be specific, the white pigment).

[0102] An example of the filler includes a known filler, except for the
above-described white pigment. To be specific, an inorganic filler is
used. Examples thereof include silica powder, talc powder, alumina
powder, aluminum nitride powder, and silicon nitride powder.

[0103] Preferably, as the filler, the silica powder is used from the
viewpoint of reducing a linear expansion coefficient of the reflecting
resin layer 4.

[0105] Examples of the shape of the filler include, for example, a sphere
shape, a plate shape, and a needle shape. Preferably, the sphere shape is
used from the viewpoint of excellent filling characteristics and
fluidity.

[0106] Therefore, preferably, the fused silica powder in a sphere shape is
used as the silica powder.

[0107] The average value of the maximum length (in a case of the sphere
shape, the average particle size) of the filler is in the range of, for
example, 5 to 60 μm, or preferably 15 to 45 μm. The average value
of the maximum length is measured by using the laser diffraction
scattering particle size analyzer.

[0108] The addition ratio of the filler is adjusted so that the total
amount of the filler and the light reflecting component per 100 parts by
mass of the resin is, for example, 10 to 80 parts by mass. And the
addition ratio of the filler is adjusted so that the total amount of the
filler and the light reflecting component per 100 parts by mass of the
resin is preferably 25 to 75 parts by mass, or more preferably 40 to 60
parts by mass from the view point of reducing the linear expansion
coefficient and ensuring the fluidity.

[0109] The above-described resin, light reflecting component, and filler,
which is added as required, are blended to be uniformly mixed, so that
the reflecting resin composition is prepared.

[0110] Also, the reflecting resin composition is prepared in a B-stage
state.

[0111] The reflecting resin composition is formed, for example, in a state
of liquid or semi-solid and has a kinetic viscosity in the range of for
example, 10 to 30 mm2/s.

[0112] The reflecting resin layer 4 has a thickness in the range of, for
example, 25 to 500 μm, or preferably 50 to 300 μm.

[0113] Next, a method for producing the above-described light emitting
diode device 1 is described with reference to FIGS. 1 to 3.

[0114] In this method, as shown in FIG. 2(b), a reflecting resin sheet 13
is first prepared.

[0116] The reflecting resin sheet 13 includes a first release substrate 21
and the reflecting resin layer 4 provided on the upper surface (one
surface in the thickness direction) of the first release substrate 21.

[0117] To obtain the reflecting resin sheet 13, as referred in FIG. 2(a),
the reflecting resin layer 4 is first provided on the upper surface (one
surface in the thickness direction) of the first release substrate 21 to
obtain a laminated sheet 17.

[0118] To provide the reflecting resin layer 4 on the upper surface of the
first release substrate 21, for example, the first release substrate 21
is first prepared.

[0119] The first release substrate 21 is formed of a resin material and
the like such as a vinyl polymer including polyolefin (to be specific,
polyethylene and polypropylene) and ethylene-vinyl acetate copolymer
(EVA); a polyester including polyethylene terephthalate and
polycarbonate; and a fluorine resin including polytetrafluoroethylene.
The first release substrate 21 is also formed of a metal material such as
iron, aluminum, or stainless steel.

[0120] The first release substrate 21 has a thickness in the range of, for
example, 10 to 1000 μm.

[0121] Next, the reflecting resin layer 4 is laminated over the entire
upper surface (one surface in the thickness direction) of the first
release substrate 21.

[0122] To laminate the reflecting resin layer 4 over the entire upper
surface of the first release substrate 21, the reflecting resin
composition is applied onto the entire upper surface of the first release
substrate 21, for example, by a known application method such as a
dispenser. In this way, a reflecting film is formed and by heating the
formed reflecting film, the reflecting resin layer 4 in a sheet state is
obtained. The reflecting resin layer 4 is brought into a B-stage state by
being heated.

[0123] The heating conditions include a heating temperature in the range
of, for example, 40 to 150° C., or preferably 50 to 140° C.
and a heating time in the range of, for example, 1 to 60 minutes, or
preferably 3 to 20 minutes.

[0124] In this way, the laminated sheet 17 including the first release
substrate 21 and the reflecting resin layer 4 laminated on the upper
surface thereof is obtained.

[0125] Thereafter, as shown in FIG. 2(b), through holes 9 are formed to
extend through the laminated sheet 17 in the thickness direction.

[0126] That is, as referred in FIG. 2(c), the through holes 9 are formed
so as to correspond to the light emitting diode elements 3. To be
specific, when the reflecting resin sheet 13 that is turned over upside
down is laminated on the diode board 2, the through holes 9 are formed
into shapes (to be specific, generally rectangular shapes in plane view)
which are substantially the same as those of the regions where the light
emitting diode elements 3 and the phosphor layers 5 are disposed and in
which the inner circumference surfaces of the through holes 9 in the
reflecting resin layer 4 can be disposed in opposed relation to the
respective side surfaces of the light emitting diode elements 3 and the
phosphor layers 5.

[0127] The maximum length of the through hole 9 is not particularly
limited and is in the range of, for example, 1 to 10000 μm.

[0128] To form the through holes 9 in the laminated sheet 17, a known
perforation method such as etching (for example, dry etching), punching
using a mold die, or drilling is used.

[0129] In this way, the first release substrate 21 and the reflecting
resin layer 4 are perforated to communicate with each other and the
through holes 9 having the above-described pattern are formed in the
laminated sheet 17.

[0130] In this way, the reflecting resin sheet 13 can be formed.

[0131] Next, in this method, as shown in the lower portion in FIG. 2(c),
the reflecting resin sheet 13 is laminated on the diode board 2.

[0132] That is, the reflecting resin sheet 13 shown in FIG. 2(b) is first
turned over upside down.

[0133] Then, the turned over reflecting resin sheet 13 is laminated on the
upper surface (one surface in the thickness direction) of the diode board
2 so that the reflecting resin layer 4 is in contact with the diode board
2.

[0134] Next, in this method, as shown in the upper portion in FIG. 2(c),
the light emitting diode elements 3 each having the phosphor layer 5
laminated on the upper surfaces thereof are prepared.

[0135] To be specific, the phosphor layer 5 is first prepared and then,
the light emitting diode elements 3 are laminated on the upper surface of
the phosphor layers 5. Thereafter, the phosphor layers 5 and the light
emitting diode elements 3 are turned over upside down.

[0136] When the phosphor layer 5 is formed of the phosphor composition,
the phosphor composition is, for example, applied onto the upper surface
of a release film not shown to form a phosphor film (not shown). Then,
the phosphor film is heated at, for example, 50 to 150° C. to be
dried, so that the phosphor layer 5 in a sheet state is obtained.
Thereafter, the release film is peeled off from the phosphor layer 5.

[0137] Alternatively, when the phosphor layer 5 is formed of a ceramic of
a phosphor (phosphor ceramic plate), for example, the above-described
phosphor is used as a ceramic material, which is formed into a sheet
state, and then is sintered to obtain the phosphor layer 5 (phosphor
ceramic) in a sheet state.

[0138] Next, the light semiconductor layer 7 is formed on the upper
surface of the phosphor layer 5 in a predetermined pattern by a known
growth method such as an epitaxial growth method. Then, the electrode
portions 8 are formed on the upper surface of the light semiconductor
layer 7 in the above-describe pattern.

[0139] In this way, the light emitting diode elements 3 are formed on the
upper surface of the phosphor layer 5. Then, a cutting (dicing) process
is performed to form generally rectangular shapes in plane view with
predetermined sizes as required, each of which includes at least one
piece of the light emitting diode element 3 (ref: FIG. 1).

[0140] Thereafter, the phosphor layers 5 and the light emitting diode
elements 3 are turned over upside down to prepare the light emitting
diode elements 3 having the phosphor layers 5 laminated on the upper
surfaces thereof.

[0141] Next, as shown in FIG. 2(d), the light emitting diode elements 3
are disposed on the upper surface (one surface in the thickness
direction) of the diode board 2.

[0142] To be specific, the light emitting diode elements 3 are disposed in
the through holes 9 of the reflecting resin sheet 13 to be flip mounted
on the diode board 2. The flip mounting (also called flip-chip mounting)
is performed by electrically connecting the electrode portions 8 to the
terminals 6.

[0143] Thereafter, as shown in FIG. 3(e), a buffer sheet 26 is provided on
the upper surface of the reflecting resin sheet 13.

[0144] The buffer sheet 26 is a sheet (a cushion sheet) that buffers a
pressing force so as not to allow the pressing force to non-uniformly
apply to the light emitting diode elements 3 in the pressing to be
described next (ref: the arrow in FIG. 3(e)). The buffer sheet 26 is
formed of, for example, an elastic sheet (film) and the like.

[0145] A buffer material for forming the buffer sheet 26 includes the same
resin material as that for forming the first release substrate 21
described above. Preferably, the buffer sheet 26 is formed of vinyl
polymer, or more preferably, the buffer sheet 26 is formed of EVA.

[0146] The buffer sheet 26 has a thickness in the range of, for example,
0.01 to 1 mm, or preferably 0.05 to 0.2 mm.

[0147] To be specific, the buffer sheet 26 is, in plane view, formed on
the upper surface of the reflecting resin sheet 13 (the first release
substrate 21) including the through holes 9.

[0148] Subsequently, as shown by the arrow in FIG. 3(e), the reflecting
resin sheet 13 is pressed toward the lower side.

[0149] To be specific, the reflecting resin sheet 13 with respect to the
diode board 2 is pressed via the buffer sheet 26, for example, with a
pressing machine or the like.

[0150] The pressure is in the range of, for example, 0.01 to 7 MPa, or
preferably 0.05 to 4 MPa.

[0151] The above-described pressing can be performed together with heating
as required. That is, hot pressing (to be specific, hot pressing in which
the pressing is performed with a hot plate) can be performed.

[0152] The heating temperature is in the range of, for example, 25 to
140° C.

[0153] Since the reflecting resin layer 4 is sandwiched between the first
release substrate 21 and the diode board 2, the pressing force applied to
the reflecting resin layer 4 in the thickness direction transmits to the
side, to be specific, outwardly (leftwardly, rightwardly, forwardly, and
rearwardly) in the plane direction. In this way, the reflecting resin
layer 4 comes in close contact with the respective side surfaces (the
left surfaces, the right surfaces, the front surfaces, and the rear
surfaces) of the light emitting diode elements 3 and the phosphor layers
5.

[0154] As referred in the phantom lines in FIG. 2(d), when the light
emitting diode elements 3 are disposed in the through holes 9, minute
side space 27 may be formed between the inner circumference surfaces of
the through holes 9 in the reflecting resin layer 4 and the side surfaces
of the light emitting diode elements 3. In that case, by the
above-described pressing, the reflecting resin layer 4 also fluidly moves
outwardly (leftwardly, rightwardly, forwardly, and rearwardly) in the
plane direction, so that the side space 27 are filled with the reflecting
resin layer 4.

[0155] By the above-described pressing, the lower space 12 are also filled
with the reflecting resin layer 4. Therefore, the reflecting resin layer
4 with which the lower space 12 are filled comes in close contact with
the lower surfaces of the light semiconductor layers 7 and the side
surfaces of the electrode portions 8.

[0156] Then, as shown in FIG. 3(f), the buffer sheet 26 (ref: FIG. 3(e))
is removed and subsequently, the first release substrate 21 (ref: FIG.
3(e)) is peeled off from the reflecting resin layer 4.

[0157] Then, the reflecting resin layer 4 in a B-stage state is cured by
being heated.

[0158] In this way, as shown in FIG. 1, the assembly sheet 24 including a
plurality of the light emitting diode devices 1 arranged in alignment is
obtained.

[0159] Thereafter, as shown by the dash-dot lines in FIG. 1 and the
dash-dot lines in FIG. 3(f), the diode board 2 and the reflecting resin
layer 4, which are located between the light emitting diode elements 3
adjacent to each other, are subjected to a cutting (dicing) process along
the thickness direction.

[0160] In this way, the light emitting diode elements 3 are cut into
plural pieces. That is, the light emitting diode elements 3 are
individualized (singulated).

[0162] In the above-described method, the reflecting resin layer 4 is
brought into close contact with the side surfaces of the light emitting
diode elements 3.

[0163] Also, in this method, the first release substrate 21 is pressed
toward the diode board 2, so that the reflecting resin layer 4 sandwiched
between the first release substrate 21 and the diode board 2 in the
thickness direction fluidly moves to the side. Since the inner
circumference surfaces of the through holes 9 in the reflecting resin
layer 4 and the side surfaces of the light emitting diode elements 3 are
disposed in opposed relation, the reflecting resin layer 4 can be
reliably brought into close contact with the side surfaces of the light
emitting diode elements 3.

[0164] Therefore, in the light emitting diode device 1 obtained by the
above-described method, light emitted from the light emitting diode
element 3 to the side is reflected by the reflecting resin layer 4 before
being absorbed by another member.

[0165] Moreover, the light emitting diode device 1 can emit high-energy
white light by color mixing of the blue light emitted from the light
emitting diode element 3 upward and the yellow light that is converted in
wavelength by the phosphor layer 5.

[0166] As a result, the extraction efficiency of the light can be
improved.

[0167] FIGS. 4 and 5 show process drawings for illustrating another
embodiment (an embodiment in which a second release substrate is used) of
a method for producing the light emitting diode device of the present
invention.

[0168] In the embodiments in FIGS. 2 and 3, the substrate in the producing
method of the light emitting diode device of the present invention is
described as the diode board 2. Alternatively, for example, as shown in
FIGS. 4 and 5, it is also possible to obtain the light emitting diode
devices 1 by using a second release substrate (release substrate) 23 as
the substrate and separately preparing the diode board 2.

[0169] Next, a method for producing the light emitting diode device 1
using the second release substrate 23 is described with reference to
FIGS. 4 and 5. In FIGS. 4 and 5, the same reference numerals are provided
for members corresponding to each of those described above, and their
detailed description is omitted.

[0170] In this method, as shown in FIG. 4(a), the laminated sheet 17
including the first release substrate 21 and the reflecting resin layer 4
is first prepared. Subsequently, as shown in FIG. 4(b), the through holes
9 are formed in the laminated sheet 17 to prepare the reflecting resin
sheet 13.

[0171] Subsequently, as shown in the lower portion in FIG. 4(c), the
reflecting resin sheet 13 is turned over upside down and then, is
laminated on the upper surface of the second release substrate 23 as the
substrate.

[0172] The second release substrate 23 is formed of the same material as
that for the first release substrate 21 described above. The second
release substrate 23 can also be formed of a thermal release sheet that
can be easily peeled off from the light emitting diode elements 3 and the
reflecting resin layer 4 by being heated. As shown in the phantom lines
in FIG. 4(c), for example, the thermal release sheet includes a
supporting layer 15 and a pressure-sensitive adhesive layer 16 laminated
on the upper surface of the supporting layer 15.

[0173] The supporting layer 15 is formed of, for example, a heat resistant
resin such as polyester.

[0174] The pressure-sensitive adhesive layer 16 is formed of, for example,
a thermally expandable pressure-sensitive adhesive and the like, which
has adhesion under normal temperature (25° C.), and in which the
adhesion is reduced (or lost) at the time of being heated.

[0175] A commercially available product can be used as the above-described
thermal release sheet. To be specific, REVALPHA (a trade name,
manufactured by NITTO DENKO CORPORATION) and the like can be used.

[0176] The thermal release sheet reliably supports the reflecting resin
layer 4 and the light emitting diode elements 3 by the supporting layer
15 via the pressure-sensitive adhesive layer 16 and is peeled off from
the light emitting diode elements 3 and the reflecting resin layer 4 due
to a reduction in the adhesion of the pressure-sensitive adhesive layer
16 by the heating and thermal expansion performed thereafter.

[0177] The second release substrate 23 has a thickness in the range of,
for example, 10 to 1000 μm.

[0178] Next, as shown in FIG. 4(d), the light emitting diode elements 3
are provided on the upper surface of the second release substrate 23.

[0179] To be specific, the light emitting diode elements 3 are disposed in
the through holes 9 of the reflecting resin sheet 13. In this way, the
inner circumference surfaces of the through holes 9 in the reflecting
resin sheet 13 are disposed in opposed relation to the respective side
surfaces of the light emitting diode elements 3 and the phosphor layers
5. The light emitting diode elements 3 are also disposed in the through
holes 9 so as to bring the phosphor layers 5 into contact with the second
release substrate 23.

[0180] Next, as shown in FIG. 5(e), the buffer sheet 26 is provided on the
upper surface of the reflecting resin sheet 13. Subsequently, as shown by
the arrow in FIG. 5(e), the reflecting resin sheet 13 is pressed toward
the lower side to bring the reflecting resin layer 4 into close contact
with the respective side surfaces of the light emitting diode elements 3
and the phosphor layers 5.

[0182] Subsequently, as shown by the dash-dot lines in FIG. 5(f), the
second release substrate 23, the reflecting resin layer 4, and the first
release substrate 21, which are located between the light emitting diode
elements 3 adjacent to each other, are subjected to a cutting (dicing)
process along the thickness direction.

[0183] In this way, the light emitting diode elements 3 are cut into
plural pieces. That is, as shown in FIG. 5(g), the light emitting diode
elements 3 having the side surfaces thereof in close contact with the
reflecting resin layer 4 are individualized (singulated).

[0184] Then, as shown in the phantom lines in FIG. 5(g), the first release
substrate 21 is peeled off from the reflecting resin layer 4, while the
second release substrate 23 is peeled off from the light emitting diode
element 3 and the reflecting resin layer 4. When the second release
substrate 23 is formed of a thermal release sheet, the second release
substrate 23 is peeled off by being heated.

[0185] Then, as shown in FIG. 5(h), the light emitting diode element 3 is
turned over upside down and is flip mounted on the diode board 2.

[0186] In the flip mounting, the reflecting resin layer 4 is in a B-stage
state so that the lower surface thereof is adhered to the upper surface
of the diode board 2, while the reflecting resin layer 4 is buried in the
lower space 12 (ref: FIG. 2(d)). Thereafter, the reflecting resin layer 4
is cured by being heated, so that the light emitting diode element 3 is
encapsulated by the reflecting resin layer 4.

[0187] In this way, the light emitting diode device 1 is obtained.

[0188] The embodiments in FIGS. 4 and 5 can achieve the same function
effect as achieved by the embodiments in FIGS. 2 and 3.

[0189] Additionally, in the embodiments in FIGS. 4 and 5, the light
emitting diode element 3 which has the side surfaces thereof in close
contact with the reflecting resin layer 4 and from which the second
release substrate 23 is peeled off is flip mounted on the diode board 2,
so that the light emitting diode device 1 can be easily produced.

[0190] On the other hand, according to the embodiments in FIGS. 2 and 3,
when the reflecting resin sheet 13 formed with the through holes 9 is
accurately disposed on the diode board 2, by subsequently disposing the
light emitting diode elements 3 in the through holes 9 of the reflecting
resin sheet 13, it is possible to easily and reliably perform accurate
positioning of the light emitting diode element 3 with respect to the
diode board 2 and flip mount the light emitting diode elements 3 on the
diode board 2.

EXAMPLES

[0191] While the present invention will be described hereinafter in
further detail with reference to Examples, the present invention is not
limited to these Examples.

[0193] That is, a first release substrate made of polyethylene
terephthalate having a thickness of 25 μm was first prepared. Then,
100 parts by mass of thermosetting silicone resin and 20 parts by mass of
a particle of titanium oxide (TiO2: tetragonal system of rutile) in
a sphere shape having an average particle size of 300 nm were uniformly
mixed, so that a reflecting resin composition was prepared. The prepared
reflecting resin composition was applied on the entire upper surface of
the first release substrate to form a reflecting film. Thereafter, by
heating the reflecting film, a reflecting resin layer in a B-stage state
having a thickness of 100 μm was formed over the entire upper surface
of the first release substrate to form a laminated sheet including the
first release substrate and the reflecting resin layer (ref: FIG. 2(a)).

[0194] Then, through holes in rectangular shapes in plane view each having
a maximum length of 400 μm were formed in the laminated sheet by
punching using a mold die. In this way, the reflecting resin layer was
prepared (ref: FIG. 2(b)).

[0195] Next, the reflecting resin sheet was turned over upside down.
Thereafter, the turned over reflecting resin sheet was laminated on the
upper surface of a diode board having a thickness of 1 mm (ref: the lower
portion in FIG. 2(c)).

[0196] Separately, phosphor layers were prepared. Then, light emitting
diode elements were laminated on the upper surfaces of the phosphor
layers. To be specific, a release film was first prepared. Thereafter, 26
parts by mass of phosphor particles composed of
Y3Al5O12:Ce (in a sphere shape, the average particle size
of 8 μm) and 74 parts by mass of a silicone resin (addition reaction
type silicone resin, kinetic viscosity (at 25° C.) of 20
mm2/s, manufactured by WACKER ASAHIKASEI SILICONE CO., LTD.) were
blended and stirred uniformly, so that a phosphor composition was
prepared. The phosphor composition was applied on the entire upper
surface of the prepared release film to form a phosphor film. Then, the
phosphor film was dried at 100° C. to form a phosphor layer on the
entire upper surface of the release film. Thereafter, the release film
was peeled off from the phosphor layers.

[0197] Subsequently, light emitting diode elements each having a thickness
of 0.1 mm and including a light semiconductor layer including a buffer
layer (GaN); an N-type semiconductor layer (n-GaN); a light emitting
layer (InGaN); and a P-type semiconductor layer (p-GaN:Mg) and an
electrode portion including an anode electrode and a cathode electrode
were formed on the upper surfaces of the phosphor layers. In this way,
the light emitting diode elements having the phosphor layers laminated on
the lower surfaces thereof were formed.

[0198] Thereafter, the light emitting diode elements and the phosphor
layers were turned over upside down (ref: the upper portion in FIG.
2(c)).

[0199] Then, the light emitting diode elements were disposed on the upper
surface of a diode board (ref: FIG. 2(d)). To be specific, the light
emitting diode elements were disposed in the through holes of the
reflecting resin sheet and were flip mounted on the diode board. The flip
mounting was performed by electrically connecting the electrode portions
and terminals. The inner circumference surfaces of the through holes in
the reflecting resin layer and the side surfaces of the light emitting
diode elements were disposed in opposed relation in a plane direction.

[0200] Thereafter, a buffer sheet made of EVA having a thickness of 0.12
mm was provided on the upper surface of the reflecting resin sheet (ref:
FIG. 3(e)).

[0201] Then, the reflecting resin sheet with respect to the diode board
was pressed via the buffer sheet at a pressure of 0.3 MPa with a pressing
machine (ref: the arrow in FIG. 3(e)). In this way, the reflecting resin
layer was brought into close contact with the respective side surfaces of
the light emitting diode elements and the phosphor layers.

[0202] Then, the buffer sheet was removed. Subsequently, the first release
substrate was peeled off from the reflecting resin layer (ref: FIG.
3(f)). Thereafter, the reflecting resin layer was cured by being heated.

[0203] In this way, an assembly sheet including a plurality of the light
emitting diode devices arranged in alignment was obtained (ref: FIG. 1).

[0204] Thereafter, the diode board and the reflecting resin layer, which
were located between the light emitting diode elements adjacent to each
other, were subjected to a dicing process along a thickness direction
(ref: the dash-dot lines in FIG. 1 and the dash-dot lines in FIG. 3(f)).

[0206] In the same manner as in Example 1, a laminated sheet was formed to
form through holes and subsequently, a reflecting resin sheet was
prepared (ref: FIGS. 4(a) and 4(b)).

[0207] Then, the reflecting resin sheet was turned over upside down.
Thereafter, the turned over reflecting resin sheet was laminated on the
upper surface of a second release substrate formed of a thermal release
sheet (trade name of REVALPHA, manufactured by NITTO DENKO CORPORATION)
having a thickness of 100 μm (ref: the lower portion in FIG. 4(c)).

[0208] In the same manner as in Example 1, light emitting diode elements
were laminated on the upper surfaces of phosphor layers prepared
according to the following description and the light emitting diode
elements and the phosphor layers were turned over upside down (ref: the
upper portion in FIG. 4(c)).

<Preparation of Phosphor Layer>

[0209] 4 g of phosphor particles composed of Y3Al5O12:Ce
(in a sphere shape, the average particle size of 95 nm); 0.21 g of
poly(vinyl butyl-co-vinyl alcohol co vinyl alcohol) (manufactured by
Sigma-Aldrich Co., the weight average molecular weight of 90000 to
120000) serving as a binder resin; 0.012 g of silica powder (manufactured
by Cabot Corporation, the trade name of "CAB-O-SIL HS-5") serving as a
sintering aid; and 10 mL of methanol were mixed in a mortar to provide a
slurry. From the obtained slurry, methanol was removed using a drier to
obtain dry powder.

[0210] With 700 mg of the dry powder, a uniaxial press mold die of 20
mm×30 mm size was filled. Then, the dry powder was pressed at a
pressure of about 10 tons using a hydraulic pressing machine to obtain a
green body in a plate shape molded in a rectangular shape having a
thickness of about 350 μm.

[0211] The obtained green body was heated in air at a temperature rising
rate of 2° C./min to reach the temperature of 800° C. in a
tubular electric furnace made of alumina so that an organic component
such as the binder resin was decomposed/removed, followed by the
evacuation of the electric furnace using a rotary pump and 5-hour heating
at 1500° C. In this way, phosphor layers each formed of a ceramic
plate (YAG-CP) of a YAG:Ce phosphor having a thickness of about 280 μm
were prepared.

[0212] Then, the light emitting diode elements were disposed on the upper
surface of the second release substrate (ref: FIG. 4(d)). To be specific,
the light emitting diode elements and the phosphor layers were disposed
in the through holes of the reflecting resin sheet. The inner
circumference surfaces of the through holes in the reflecting resin layer
and the respective side surfaces of the light emitting diode elements and
the phosphor layers were disposed in opposed relation in the plane
direction.

[0213] Thereafter, a buffer sheet made of EVA having a thickness of 0.12
mm was provided on the upper surface of the reflecting resin sheet (ref:
FIG. 5(e)).

[0214] Then, the reflecting resin sheet with respect to the second release
substrate was pressed via the buffer sheet at a pressure of 0.3 MPa with
a pressing machine (ref: the arrow in FIG. 5(e)).

[0215] In this way, the reflecting resin layer was brought into close
contact with the respective side surfaces of the light emitting diode
elements and the phosphor layers.

[0217] Thereafter, the second release substrate, the reflecting resin
layer, and the first release substrate, which were located between the
light emitting diode elements adjacent to each other, were subjected to a
dicing process along the thickness direction (ref: the dash-dot lines in
FIG. 5(f)). In this way, the light emitting diode elements having the
side surfaces thereof in close contact with the reflecting resin layer
were individualized (ref: FIG. 5(g)).

[0218] Then, the first release substrate was peeled off from the upper
surface of the reflecting resin layer, while the second release substrate
was peeled off from the respective lower surfaces of the light emitting
diode element and the reflecting resin layer by being heated (ref: the
phantom lines in FIG. 5(g)).

[0219] Thereafter, the light emitting diode elements were turned over
upside down and were flip mounted on a diode board (ref: FIG. 5(h)). In
the flip mounting, the reflecting resin layer was cured by being heated
to encapsulate the light emitting diode elements (the side surfaces
thereof).

[0220] In this way, the light emitting diode devices were obtained.

[0221] While the illustrative embodiments of the present invention are
provided in the above description, such is for illustrative purpose only
and it is not to be construed as limiting the scope of the present
invention. Modification and variation of the present invention that will
be obvious to those skilled in the art is to be covered by the following
claims.